Über Pterinchemie. Mitteilung. Die Kristallstruktur von 5,6,7‐Trimethyl‐5,6,7,8‐tetrahydropterindihydrochlorid‐monohydrat

The crystal structure of 5,6,7‐trimethyl‐5,6,7,8‐tetrahydropterine‐dihydrochloride‐monohydrate The crystal structure of the title compound has been determined by X‐ray analysis (direct methods) and refined with 947 structure amplitudes to R = 0.026. The crystal system is orthorhombic, space group Pna2 1 , with unit cell dimensions a = 14.081, b = 14.623, c = 6.773 Å. The molecule is protonated at the N(1)‐ and N(5)‐position. The tetrahydropyrazine ring exists in a conformation in which C(6) deviates markedly from the mean plane of the other five atoms. The CH 3 ‐groups at N(5) and C(6) possess a trans configuration with a pseudoaxial and an axial conformation respectively. The CH 3 ‐groups at C(6) and C(7) in return possess the cis configuration, whereby the CH 3 ‐group at C(7) occupies an equatorial conformation.